Human Anatomy and Physiology

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Human Anatomy and Physiology. The Respiratory System. Basic functions of the respiratory system: Gas exchange – supply oxygen to aerobic tissues in the.

Human Anatomy and Physiology The Respiratory System Basic functions of the respiratory system: Gas exchange – as a

supply oxygen to aerobic tissues in the body and remove carbon dioxide waste product.

-Pulmonary ventilation in- to and (ventilation).

blood (thus the cell capillaries unloading

the physics of getting air out- of the lungs

-External respiration - gas exchange between the lungs and blood (oxygen loading and CO2 unloading). -Transport of respiratory gases movement of gases) from the lungs to and tissues. -Internal respiration – gas exchange between the and the tissues (oxygen and CO2 loading).

Human Anatomy and Physiology The Respiratory System Functional anatomy of the respiratory system: Conducting Zone Rigid conduits for air to reach site of gas exchange -nose -nasal cavity -pharynx -larynx -trachea -bronchi

-Respiratory Zone site of gas exchange -respiratory bronchioles -alveolar ducts

Human Anatomy and Physiology The conducting zone Conducting Zone: Nose -airway -moistens and warms air -filters inspired air -resonating chamber for speech -olfaction

-paranasal sinuses -frontal, sphenoid, ethmoid and maxillary bones -warm and moisten air

Human Anatomy and Physiology The conducting zone Conducting Zone: Pharynx -connects the nasal cavity and mouth to the larynx and esophagus -common pathway for food and air (throat) -nasopharynx -oropharynx -laryngopharynx

Human Anatomy and Physiology The conducting zone Conducting Zone: Laryngopharynx – common passage way for food and air Larynx – voice box

Human Anatomy and Physiology The conducting zone Conducting Zone: Trachea -windpipe -larynx at division forming two primary bronchi at midthorax -mucosa – pseudostratified epithelium (goblet cells) -submucosa – connective tissue seromucous glands – mucous -advantitia – CT hyaline cartilage

Human Anatomy and Physiology The conducting zone Conducting Zone: Bronchi Bronchial tree -left and right primary bronchi -formed by divisions of the trachea -secondary bronchi (lobar) -inside the lungs -3 on the right -2 on the left -tertiary bronchi (segmental) -fourth-order -fifth-order -23 orders of branching air ways -bronchioles (under 1 mm in diameter

Human Anatomy and Physiology The conducting zone Conducting Zone: Bronchioles -bronchioles (under 1 mm in diameter) -terminal bronchioiles (less than 0.5 mm)

Human Anatomy and Physiology The conducting zone Conducting Zone: Cartilage: -rings -irregular plates -no cartilage in bronchioles -replaced by elastic fibers

Epithelium: -pseudostratified (ciliated) -columnar (ciliated) -cuboidal in terminal bronchioles (no cilia)

Smooth Muscle: -increases as tubes get smaller

Human Anatomy and Physiology The respiratory zone Respiratory Zone: Respiratory bronchioiles Alveoli (300 million) Alveolar ducts Alveolar sacs

Gas Exchange: respiratory membrane

Human Anatomy and Physiology The respiratory zone Respiratory Zone: Respiratory membrane (air-blood barrier) or (Alveolar-capillary membrane) is composed of: -simple squamous epithelial cells (Type I cells) -cobweb of pulmonary capillaries Primary function is gas exchange -Type II cells (cuboidal) surfactant -elastic fibers -alveolar pores allow for pressure equalization between alveoli -alveolar macrophages (dust cells)

Human Anatomy and Physiology Lungs and Pleural Coverings Pleural Coverings: -double layered serosa -parietal pleura lines the thoracic wall -pulmonary or visceral pleura which covers the lung surface -pleural cavity is the space between the two layers -pleural fluid fills the cavity

Human Anatomy and Physiology Blood Supply and Innervation of the Lungs Blood supply: -Pulmonary circulation -Bronchial circulation Pulmonary arteries from the right side of the heart supply blood to the lungs. -pulmonary arteries branch profusely along with the bronchi -pulmonary capillary networks surrounding alveoli -pulmonary veins form post alveoli to carry oxygenated blood back to the heart Bronchial arteries come from the aorta and enter the lung at the hilus -the bronchial arteries run along the branching bronchi and supply lung tissue except the alveoli -bronchial veins drain the bronchi but most moves into the pulmonary circulation

Human Anatomy and Physiology Blood Supply and Innervation of the Lungs Innervation: -parasympathetic motor fibers (some sympathetic fibers) -visceral sensory fibers Enter the lung through the pulmonary plexus on the lung root parasympathetic fibers – constrict the air tubes sympathetic fibers – dilate air tubes

Human Anatomy and Physiology Respiratory Mechanics Breathing: Simply pressure changes driven by diaphragm and external intercostal muscle contractions

Human Anatomy and Physiology Respiratory Mechanics Breathing: yellow is the increase in volume during inspiration -

Volume during Inspiration Lungs

Volume At rest

Human Anatomy and Physiology Respiratory Mechanics Breathing: Increased volume causes a drop in pressure if the system is closed. Where is the system closed to the outside?

Lungs

Boyle’s law – P1V1 = P2V2

Human Anatomy and Physiology Respiratory Mechanics Breathing: Increased volume causes a drop in pressure if the system is closed. Where is the system closed to the outside? The pleural cavity!

Lungs The decrease in intrapleural cavity pressure is translated to the lungs via the inner visceral pleural membrane because it is attached to the outer surface of the lung Thus, an increase in volume causes a decrease in intrapleural pressure because it is a closed system.

Human Anatomy and Physiology Respiratory Mechanics Breathing: The lungs are an open system via the trachea and as such as intrapleural pressure drops lung volume increases and lung pressure also decreases. However, because the lungs are open to the outside, air rushes into the lungs to equalize the pressure. Thus, the drop in pulmonary pressure is transient.

Lungs

trachea

Pulmonary pressure returns to zero as air moves into the lungs to take up the volume change (drop in pressure).

Human Anatomy and Physiology Respiratory Mechanics

Human Anatomy and Physiology Respiratory Mechanics Breathing: Airway Resistance-friction or drag along the respiratory passageway P Flow = R -maximum resistance in medium size bronchi then drops as cross sectional area increases -bronchiole smooth muscle very sensitive to parasym stimulation

Human Anatomy and Physiology Respiratory Mechanics Lung volumes dead space –

-volume of air filling the conducting zone and never contributes to gas exchange (anatomical dead space 150 ml). -if some of the alveoli collapse or are obstructed (alveolar dead space). Total dead space = AnaDS + AlvDS

Human Anatomy and Physiology Respiratory Mechanics Breathing: -

Human Anatomy and Physiology Gas Exchange Gas exchange: -